The macrocyclic acetylenic ketones of formula (I) represent useful intermediates for the preparation of muscone and EXALTONE.RTM. (registered trademark of Firmenich S A, Geneva, Switzerland), two macrocyclic derivatives of musky odor widely used in perfumery.
European Patent Application No. 13995, open to public inspection on Aug. 6, 1980, describes a process for their preparation characterized in that
(a) a hydrazone of formula ##STR5## wherein R designates a hydrogen atom or a methyl radical and symbol A stands for a sulfonyl radical of formula R.sup.1 --SO.sub.2 --, wherein R.sup.1 represents an aryl group, is treated with a halogenating reagent chosen from the following group:
bromine PA1 chlorine PA1 iodine PA1 1,3-dibromo-5,5-dimethyl-hydantoin PA1 N-bromosuccinimide PA1 N-chlorosuccinimide, and PA1 N-iodosuccinimide,
in the presence of a lower aliphatic alcohol and at a temperature of between about -25.degree. and +25.degree. C.
(b) the excess of halogenating reagent is reduced, and
(c) the reaction product is heated in an aqueous medium at a temperature of between 20.degree. and 60.degree. C.
The prior art discloses also the process illustrated by the following reaction scheme: ##STR6## [see: Helv.Chim.Acta, 50, 708 (1967)].